Further south temperatures will drop as low as -7C with icy conditions a real danger overnight.

Thousands of rail workers have worked round-the-clock to stop the cold snap causing delays by keeping tracks clear of sleet, snow and ice.

A Network Rail spokesman said: ‘With temperatures set to drop below zero across the country this week, thousands of our people will be patrolling the tracks day and night to clear snow and ice and keep passengers moving.”

Chaos: People are being warned to be careful when out and about (Image: PA)

Motorists have been warned of difficult driving conditions and travel disruption, while the elderly have been urged to stay warm.

The cold snap is in sharp contrast to last month, which was both the wettest and warmest December on record, when temperatures averaged 7.9C.

Two schools in Northumberland had to close because of severe weather conditions while the East of England was buffeted by gales of 50 to 60 miles an hour.

Snow joke: Cars make their way through the snow on the A1 northbound in Gateshead (Image: PA)

Two men aged 35 and 40 from Wakefield were rescued from a gully in Snowdonia which was at risk of being hit by an avalanche.

The Met Office’s Lindsay Mears said: “Saturday is going to be a very very cold night everywhere dropping to -7C in the south and further north it will drop as low to -15C in the exposed mountainous areas in Scotland.

“There is also the possibility of some freezing fog in Yorkshire, Lincolnshire on Saturday morning.

Ploughing through: Gritters are out in force on the UK's roads

“Althought for most people over the weekend it will be quite sunny and bright but it will be very, very cold and then Saturday night we’re expecting very low temperatures.

“We believe next week it will get a little less cold but we’re not sure when that will be yet.”

The Met Office has issued a Level-2 Cold Weather alert to warn councils and the NHS about the dangers caused by the freezing temperatures.

Councils have stockpiled 1.2million tons of salt and are preparing to grit thousands of miles of roads when overnight temperatures plummet in the next few days.

Environment spokesman for the Local Government Association Cllr Peter Box, said: “Councils are fully prepared to protect residents and minimise disruption to their residents caused by the drop in temperatures.

"As well as gritting our roads and clearing snow, council teams are ready to be drafted in to help provide a variety of services to ensure we are looking out for the more vulnerable members of our communities this winter, from carrying out emergency household repairs to delivering hot meals and portable heaters.

Bracing: Children make their way to school through the snow in Washington, Tyne and Wear (Image: PA)

“But council staff can’t be everywhere. They rely on community-spirited residents to look out for each other.

"Just a quick knock on the door of an elderly neighbour who’s perhaps too proud or unable to ask for help can make all the difference.

"They may just need an extra blanket getting down from the loft or perhaps they didn’t get out to collect their medicine this week.

"It takes no time to check in but could potentially save lives.”

Older people’s charity Independent Age have warned the elderly and their families and carers to take extra care.

Neighbourly: People are being urged to take care of their elderly family and neighbours (Image: PA)

Lucy Harmer, Director of Services at Independent Age, said, “Winter can be a testing time for many elderly people if they don’t have enough social, financial or emotional support in place.

"We would urge older people, their families and carers to take extra care during the cold snap.

"The government, councils and individuals all need to take more responsibility for ensuring older people are getting the support they need in winter.”

Last year, the ONS found that an estimated 36,300 excess winter deaths occurred in England and Wales in 2014/15 among people aged 75 and over.

A poll published by Independent Age last month found an estimated 752,000 older people have had to choose between paying for food and paying for heating and almost half (43%) of those aged 65 and over say they have gone to bed early to stay warm at least once.